A filament reel holder that uses Airsoft bb's as bearings

here is a filament reel holder that sets, or can be bolted to a 20x20 rail. it uses airsoft bb's as ball bearings. line the notches up in the bearing and you can pop in the last few bb's. it can use a t-slot nut to hold 1 rail, while you leave the other one just sitting on the 2020 rail. then you can just slide 1 around to accommodate different widths of reels. the bearings are held on the braces using 3mm x 7mm or longer bolts.